I've already pre-ordered my Lumia 900. Granted, I was an early adopter dork for Windows Phone 7, getting a Samsung Focus the week it came out (and off contract, no less). Had a chance to play with the Lumia during my brother's lunch break (he works at AT&T), and really liked it. The camera, larger screen and hot-spot ability were major selling points for me, so I went ahead and used my upgrade. Really excited, and looking forward to getting it ^_^
Now, that said, I have to readily admit that while I'm a big fan of WP7 and its aesthetic, I can't really recommend it to anyone. For most users I send them straight to iPhones. If they're power users? Android. As such, while I love my chosen platform dearly, I don't have any really compelling reason to recommend it. Similarly, its actually kind of hard to really, quickly, articulate why I love the damn thing so much, at least features-wise. Some of the stuff is easy, some of it takes some explaining, but at least for me none of it is immediately obvious. I've been following WP7 since Paul Thurott first started talking about it, been using it since launch, etc., so its not like I don't have a wealth of reasons to love it!
I love WP7, but Microsoft and Nokia really need to get their marketing pumping now and for WP8, because its really hard to user-evangelize. I've heard some people talk about tech bloggers and other folks who are crooning praises over it, but lets be honest - that's not enough and not really the sort of crowd the average user readily identifies with.